How to correct mistakes in your tax

If you think you've paid the wrong amount of Income Tax, or made a mistake on your Self Assessment tax return, let us know as soon as possible. It's usually quite easy to put things right by following a few simple steps.

On this page:

Why you could have paid too much or too little tax

You might have paid the wrong amount of tax because:

  • your employer used the wrong tax code
  • you had an emergency tax code
  • you only worked for part of the year
  • you had more than one job at the same time
  • you didn't tell HM Revenue & Customs (HMRC) about benefits you got through your work
  • your circumstances changed - perhaps you were made redundant
  • you're self-employed
  • you've got other income such as investments or rental income
  • you made a mistake on your tax return
  • you're on a low income but you paid tax on your savings
  • HMRC made a mistake with your tax

All of these things and more can mean that you pay too much or too little tax.

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Paid too much tax through your employment or company pension

You can claim back the extra tax. HMRC calls any money they pay back a 'repayment'.

Claiming refunds for the current tax year

Tell HMRC why you think you've paid too much. If they need more information, they'll tell you what paperwork to send.

You might get a new tax code, meaning any refund will be added to your wages or pension.

Claiming refunds for previous tax years

You'll need to write to HMRC to get any refund due. Include paperwork about your earnings in the tax year you're claiming for, like:

  • pay slips
  • forms P60 and P45
  • details of your employment - including any employee benefits you got

They'll work out how much tax you're owed and send you a repayment in the post or direct to your bank or building society if you’ve provided details of your account.

In most cases you'll get back the tax you've overpaid as long as you claim on time. The time limits for claiming a refund are shown in the table below. If you don't make a claim within the time limit you'll miss out on any refund due.

Time limits for claiming back tax
Tax year Tax year ended on You must claim by:
2010 to 11 5 April 2011 5 April 2015
2011 to 12 5 April 2012 5 April 2016
2012 to 13 5 April 2013 5 April 2017
2013 to 14 5 April 2014 5 April 2018

Find out how to claim if you've overpaid tax through your job

Find out how to claim if you've overpaid tax through your pension

Get information about claiming a repayment if you stop work

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Paid too much tax after filling in a Self Assessment tax return

There are two ways of claiming a refund, depending on the tax year you're claiming for.

Claiming for the last tax year

If you've made a mistake on your tax return, you've got 12 months from the return deadline to correct it. This is called an 'amendment'.

If you filled in a paper tax return, write to HMRC, telling them what corrections to make to which boxes on the return. If you filed your tax return online, you may be able to make your amendment online.

Find out more by following the link below.

Correcting your tax return or claiming a refund

Claiming for previous tax years

If you didn't fill in a tax return for the year in question, write to HMRC and tell them why you're claiming. If you did fill one in, write to HMRC and ask to claim 'overpayment relief'.

In most cases you'll get back the tax you've overpaid as long as you claim on time. The time limits for claiming a refund are shown in the table below. If you don't make a claim within the time limit you'll miss out on any refund due. But if HMRC has made a mistake you can get extra time.

How will any refund be made?

You should state on your tax return or letter how you would like the repayment to be made. You can have it deducted from any tax due on your next Self Assessment Statement or you can ask for it to be sent to you by post or direct to your bank or building society account.

Time limits for claiming back tax
Tax year Tax year ended on You must claim by:

2010 to 11

5 April 2011

5 April 2015

2011 to 12

5 April 2012

5 April 2016

2012 to 13

5 April 2013

5 April 2017

2013 to 14

5 April 2014

5 April 2018

Find out more about correcting your tax return or claiming a refund

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Owed tax back on savings or investment income

Tax is automatically taken off the interest on your savings and income from life annuities at the rate of 20%.

If you're on a low income, you may be able to get back some or all of the tax you've paid. You'll have to fill in a claim form.

In most cases you'll get back the tax you've overpaid as long as you claim on time. The time limits for claiming a refund are shown in the table below. If you don't make a claim within the time limit you'll miss out on any refund due.

Time limits for claiming back tax
Tax year Tax year ended on You must claim by:

2010 to 11

5 April 2011

5 April 2015

2011 to 12

5 April 2012

5 April 2016

2012 to 13

5 April 2013

5 April 2017

2013 to 14

5 April 2014

5 April 2018

Check how to get tax-free savings interest and claim tax back

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If you've paid too little tax

This is called an 'underpayment'. HMRC will usually write to you and explain why it's happened and how they'll collect the extra tax you owe. You may have to pay some interest on the tax too.

Underpayments of less than £3,000

HMRC will normally give you a new tax code and they'll ask you to pay back the tax you owe in one year.

If you want to you can pay it back straight away in one lump sum. This is called a 'voluntary payment'. Call the telephone number on the letter you received from HMRC and ask for a payslip.

Find out more about underpayments in your tax code

Underpayments of £3,000 or more

HMRC will ask you to pay the money within 30 days from the date of the letter issued or by 31 January following the end of the tax year you've underpaid - whichever is later.

Fill in the payslip HMRC sent you with their letter and send it back with your payment. Sometimes HMRC will arrange for you to pay the tax back through the Self Assessment system.

If you can't afford to pay the money you owe

Call the telephone number on the letter you received from HMRC and tell them why you can't afford to pay. You may have to give them rough figures for your income, spending, savings and other assets. They may let you spread the payments over more than one year.

How to correct 'over-repayments'

If you claimed a refund and HMRC has paid you back too much it's called an 'over-repayment'. If this happens HMRC will write to you explaining why and how they'll collect the money back.

Contact HMRC

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More useful links

Self Assessment tax return deadlines and penalties

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